iPhoto works on a Library basis. Every item is in the Library. Events are one way of looking at the Library. You can also look at it in Photos view. But it's the Library you're looking at. So, it follows: if every item is in the Library, if Events are a view of the Library, then every item is in an Event.
Don't get hung up on the word. An Event is a folder with a fancy icon.
Also, with Events, you can't have a photo in more than one Event without duplicating and wasting disk space.
Events and Albums are not Either/or - they're both.
Albums are arbitrary collections of images - you decide what goes into an Album. You might put all the images from an Event into an Album - or just the best ones. You might also combine photos from various Events into an Album. Albums contain pointers to the images in the Library. So a photo can be in 100 Albums and use no extra disk space at all. Deleting from an Album removes the photo from the Album only.
FWIW here's a canned answer I offer to illustrate some of the organising possibilities of iPhoto:
I use Events simply as big buckets of Photos: Spring 08, July - Nov 06 are typical Events in my Library. I use keywords and Smart Albums extensively. I title the pics broadly.
I keyword on a
Where basis (The When is in the photos's Exif metadata). I also rate the pics on a 1 - 5 star basis.
Using this system I can find pretty much find any pic in my 45k library in a couple of seconds.
So, for example, I have a batch of pics titled 'Seattle 08' and a typical keywording might include: John, Anne, Landscape, mountain, trees, snow. With a rating included it's so very easy to find the best pics we took at Mount Rainier.
File -> New Smart Album
set it to 'All"
title contains Seattle
keyword is mountain
keyword is snow
rating is 5 stars
Or, want a chronological album of John from birth to today?
New Smart Album
Keyword is John
Set the View options to Sort By Date Ascending
Want only the best pics?
add Rating is greater than 4 stars
The best thing about this system is that it's dynamic. If I add 50 more pics of John to the Library tomorrow, as I keyword and rate them they are added to the Smart Album.
In the end, organisation is about finding the pics. The point is to make locating that pic or batch of pics findable fast. This system works for me.
A smart album is the answer to a question - it is described in iPhoto help
so a smart album might be o=all of thephotos taken by a certain camera - or taken between July 3 and July 10 in 1998 and 2013 - or with the key word "hay" - or any of many. many other criteria - look under th efile menu ==> new smart album and play - you can delete them after playing if they are not interesting